Boat U.S. - January 2009 - (Page 29)

not be recoverable. Gel cell and AGM batteries can withstand being left in a deeply discharged condition for a longer period of time; however, prompt recharging is recommended for all batteries. To obtain maximum life from a deep-cycle battery of any type, it’s best to limit the level of discharge to about 50%, 12.2 volts (measured with no load applied). Promptly recharge the battery when the voltage drops to that level. Managing the battery in this way will yield the greatest amount of ampere-hours over the life of the battery. Running On One Engine acht with twin diesels. We’re hearing about people with twin engines running their boat on only one engine to save fuel. Does this put too much strain on the one running engine? Do you really save any fuel by running only one at a time? Laurie Fredrick Waterport, NY Q. We have a 42-foot motory- A. Running your boat on one engine, with the operating engine turning no faster the 400 rpm below maximum rated speed will not harm it. Using one engine to propel the boat at a modest speed will save fuel and reduce the wear on the engines. The fuel economy improvement will result from the fact that no power will be consumed to operate the “parasitic” loads on the inoperative engine (water pumps, fuel pump, alternator) while the operating engine will be running at a more efficient speed than if it were sharing the load with another engine. Internalcombustion engines are most efficient when delivering about 60-70% of their rated power. When an engine runs at low load (usually slowly) a greater percentage of the fuel being consumed is devoted to its own internal demand, the parasitic loads. For example the fuel consumed by an engine running in neutral at idle is devoted to simply keeping the engine turning, it’s doing no useful work. You can maximize fuel economy by running your boat at slightly less than its theoretical hull speed. (Speed in knots = about 1.2 times the square root of the waterline length in feet. For example: 7.2 knots for a boat with a 36-foot waterline.) It’s important that the prop of the inoperative engine be locked to prevent it from rotating when the boat is moving under single-engine power. Many marine transmis- sions can be damaged if the prop is allowed to rotate for a substantial period of time with the engine inoperative. Some transmissions can lock the prop if shifted into reverse with the engine off; manual and automatic prop-shaft locks are also available. Stale Water Q.We’re experiencing a stale smell from our fresh water in both of our holding tanks on a Beneteau 343. Can you recommend any water treatments that may remedy the problem? E. Jerry Jones Haleiwa, HI A. First, thoroughly flush the tanks and connecting plumbing. Fill with fresh water containing about an ounce of household bleach (plain, no soap or detergent) per gallon of water, and allow the water containing the bleach (chlorine) to stand in the tanks and plumbing for eight hours. Repeat twice. If you wish, add 16 ounces of 3-percent hydrogen peroxide (drugstore strength) to the last fill. After three flushes, fill with fresh water containing no bleach and taste the water after it’s been in the tanks for at least eight hours. If it has no disagreeable taste (remem-

Table of Contents Feed for the Digital Edition of Boat U.S. - January 2009

BoatU.S. - January 2009 Contents At The Helm Reader Forum BoatU.S. Reports Brokerage Boats Invasion Of The Access Snatchers Don’t Move A Mussel Tech Connection BoatsGearWheels A Defect And Its Aftermath Obama Onboard? Fast-Water Fly-Fishing How I Got That Shot A Loop Through The Heartland Why Boats Sink At The Dock Install Your Own Trim Tabs BoatU.S. Exchange At Your Service/Mbr. Benefits

Boat U.S. - January 2009

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